Near-room-temperature ferromagnetic ordering in the pressure-induced collapsed-tetragonal phase in SrCo2P2

TL;DR

This study demonstrates pressure-induced ferromagnetic ordering in SrCo2P2 associated with a structural transition to a collapsed tetragonal phase, combining experimental measurements and first-principles calculations to reveal the entangled nature of its properties.

Contribution

It provides the first comprehensive experimental and theoretical evidence of ferromagnetic ordering in SrCo2P2's collapsed tetragonal phase under high pressure.

Findings

Ferromagnetic ordering appears above ~10 GPa in SrCo2P2.

Structural transition to collapsed tetragonal phase occurs near 10 GPa.

Magnetic signatures vanish above ~30 GPa, indicating avoidance of quantum criticality.

Abstract

We present high pressure electrical transport, magnetization, and single crystal X-ray diffraction data on SrCo2P2 single crystals. X-ray diffraction data show that there is a transition to a collapsed tetragonal structure for p ~> 10 GPa and measurements of resistance show that above ~ 10 GPa, a clear transition-like feature can be observed at temperatures up to 260 K. Further magnetization, magnetoresistance and Hall measurements made under pressure all indicate that this transition is to a ferromagnetic ground state. First principles-based density functional theory (DFT) calculations also show that there is a first-order transition between tetragonal and collapsed tetragonal (cT) phases, with an onset near ~ 10 GPa as well as the appearance of the ferromagnetic (FM) ordering in the cT phase. Above ~ 30 GPa, the experimental signatures of the magnetic ordering vanish in a first-order-like manner, consistent with the theoretical calculation results, indicating that SrCo2P2 is another example of the avoidance of quantum criticality in ferromagnetic intermetallic compounds. SrCo2P2 provides clear evidence that the structural, electronic and magnetic properties associated with the cT transition are strongly entangled and are not only qualitatively captured by our first principles-based calculations but are quantitatively reproduced as well.